POLIMORFISMOS DA BETA CASEÍNA E SEUS IMPACTOS SOBRE A PRODUÇÃO E COMPOSIÇÃO DO LEITE NA RAÇA GIR LEITEIRO

Beta casein represents about 25-35% of the total casein in milk, with the most frequent being coded by alleles A1 and A2. The A1 variant has been linked to some diseases in humans, such as allergies, diabetes and heart disease. In order to perform an efficient selection for the A2 allele in dairy herds, it is necessary to carry out studies that relate the genotype to the milk production and composition characteristics. The objective of this study was to evaluate the relation of Beta-Casein genotypes in Gir Leiteiro cows and the production and composition of milk. 25.8% of the total animals presented heterozygous (A1A2) and 74.2% homozygous for the A2 allele. No animal from the analyzed file presented homozygous for the A1 allele agreeing with the low frequency of that allele in the breed. According to the statistical analyzes used, there was no significant difference between the genotypes and the evaluated characteristics. However, new studies on A1 / A2 polymorphism have to be performed to be used as a molecular marker in genetic selection programs.